This assessment of drivers of soil pollution in the NENA region was compiled from a review of 147 papers and reports. It revealed a wide disparity in the availability of information on soil quality, the sources and risks of soil pollution, and its remediation in each of the countries. The Islamic Republic of Iran, Kuwait, Lebanon, Palestine and Saudi Arabia are the most studied countries within the region. There is a lack of soil quality studies in Mauritania, Oman, Qatar, Sudan and Yemen. In addition to the lack of information from certain countries, there is a general lack of literature on specific topics, such as the impact of armed conflicts on soil pollution.
This review identified several sources of soil pollution in the NENA region. The arid climate, with frequent winds, contributes to the dispersion of soil contaminants by wind-blown contaminated dust in Bahrain, Egypt, Iran (Islamic Republic of), Iraq, Oman, Qatar and Saudi Arabia (Figure 2). Industry also represents a moderate source of pollution in the NENA region. The energy sector and transport density are the main sources of pollution in Algeria, Bahrain, Iran (Islamic Republic of), Iraq, Kuwait, Lebanon, Libya, Oman, Qatar, Saudi Arabia and United Arab Emirates. Agriculture is the main source of soil pollution in Palestine. It has also been reported as a significant contributor to soil pollution in Bahrain, Egypt, Iran (Islamic Republic of), Qatar, Saudi Arabia and United Arab Emirates.
However, because of limited information in the literature and lack of responses to the questionnaire from some countries, this analysis only provides a rudimentary indication of each sector’s contribution to soil pollution. From the review of environmental concerns and related legislation, it is clear that all NENA countries are interested in the environmental protection. This is often expressed in legislation on specific sectors such as water, food, forest and land. Few countries had legislation or policy documents that specifically address soil quality and soil pollution.
Soil pollution in the NENA region is linked to dense populations, dispersal of wind-blown contaminated dust, intensive oil production, mining, uncontrolled use of sewage sludge in agriculture and inappropriate waste disposal. Agricultural land can also become polluted by the inappropriate use of chemicals and pesticides in crop and livestock production (FAO and ITPS, 2015). Dust storms and erosion disperse contaminants which can adversely impact soil and water quality in the region. Oil spills during transportation in Iran (Islamic Republic of) or wars in Kuwait have contributed to severe hydrocarbons soil pollution that affected both crop production and public health.
The analysis of information in the peer-reviewed literature and national reports identified the contaminants that pose the greatest risk to human health and the environment. In order of priority, the most serious contaminants are trace elements, hydrocarbons, industrial waste and pesticides. Qatar and Sudan present a low risk of trace element contamination. Trace elements are considered a medium risk in Algeria, Bahrain, Egypt, Iraq, Iran (Islamic Republic of), Jordan, Lebanon, Libya, Morocco, Saudi Arabia, Syrian Arab Republic and United Arab Emirates. Palestine and Tunisia report some sites with alarming levels of trace elements, notably arsenic, cadmium, chromium, lead, mercury and nickel, all of which exceed ecological and human health guidelines.
Eight countries have reported the risk of pesticide transfer from soils to water and vegetation. Moderate pesticide pollution has been detected in some soils in Algeria, Egypt, Iran (Islamic Republic of), Kuwait, and Libya, while studies from Bahrain, Tunisia and Morocco had tolerable levels. In Tunisia the average annual pesticide use on land used for crop production varies between 0.2 kg/ha and 0.4 kg/ha (FAOSTAT, 2019b), measured as weight of active ingredient1. This is eight times less than that used in France and the United States of America (3-4 kg/ha), and sixty five times less than the amount of herbicides used in Thailand (13 kg/ha). Palestine uses 5 L/ha/year of pesticides, whose residues have been found in soil and water exceeding the tolerable level for crop production and causing chronic labour’s exposure (Al-Sa‵ed, Ramlawi and Salah, 2011) There are only a few studies on radionuclides and plastics that are relevant to soil pollution in the region. In some countries there are elevated background levels for some radionuclides due to the metamorphic nature of parent rock (e.g. marble, serpentinite, and gneiss).
The review identified that the NENA region does not maintain a harmonised and official list of potentially polluting activities. Iran (Islamic Republic of) reported that each year the Department of Environment prepares a list of potentially polluting industries.
From the late 1990s the issue of the long-term storage of POPs and other obsolete pesticides came to the fore. The countries, with the support of FAO and others, raised awareness of the severe risk that the stocks posed to public health and the environment, including the risk of soil pollution. At the beginning of the 2000s, the total obsolete pesticide stock in 15 of the countries was estimated at approximately 9 000 tonnes (Table 1). With support from national governments, bilateral donors, the Global Environment Facility, the pesticide industry and civil society organizations, FAO and others implemented projects to eliminate the stockpiles and build capacity in more sustainable agricultural practices that were less reliant on the use of pesticides. By 2020, the historic stockpiles in the 15 countries had been eliminated. These projects tended not to address polluted soil as the limited funds were prioritized on the elimination of concentrated pesticides to minimize the possibility for further leakage.
The review identified that the main sources of trace element contaminants are wind-blown contaminated dust and particulate matter, agricultural practices, industrial activities, solid waste management, and mining activities.
Wind-blown contaminated dust has been reported as the main source of diffuse pollution by dispersing trace elements emitted by industry and energy production and of geogenic origin. It can be found in air, water and soil in most parts of the NENA region (Figure 3). There is a growing concern in the region about the increasing frequency of dust storms from bare and desert lands, which carry particulate matter due to wind erosion. Particulate matter transports any contaminants attached to the particles. They are associated with contaminants from industrial emissions, armed conflicts and waste incineration, and can cause air and water pollution far from their point of origin when the wind-blown contaminated dust is deposited (McFee, Kelly and Beck, 1977). The levels of contamination on the dust and particulate matter are due to the prevailing methods of industrial production, energy generation and its reliance on fossil fuels.
The lack of surface water bodies means that rainfall is a major water resource for domestic, municipal, industrial and agricultural uses. Rainfall in the Western Arabian Gulf is generally not acidic (Ahmed, Singh and Elmubarak, 1990). However, locally, it can be impacted by pollution, as demonstrated by the contaminants in rain and snow in Urmia, a city in the northwest of Iran (Islamic Republic of) (Hajizadeh et al., 2017). The high levels of chlorine in the rain water correlated to those in arable fields in the west of the country and indicated the transference of contaminants on dust by the prevailing wind. The increased soil salinity may exacerbate boron (metalloid) phytotoxicity due to higher mobility under alkaline conditions (Princi et al., 2016).
Furthermore, the assessment of air quality in the Arabian Peninsula, mainly in Bahrain, Kuwait, Oman, Qatar, Saudi Arabia and United Arab Emirates revealed the presence of particulate matter, greenhouse gases, nitrogen dioxide, and sulphur dioxide emissions. These were caused by infrastructure activities, excessive use of government-subsidized energy, water desalination plants, heavy traffic in large cities and cement manufacture (Farahat, 2016). Many of these contaminants derive from the heavy use of fossil fuels in the region. The direction of the wind carrying sand and contaminated dust affects the distribution and concentration of the contaminants on the land. Human activities are an important factor in the emission of fine particulate matter with diameters less than 25 µm (PM2.5) in most countries of the Arabian Peninsula. The mixture of desert dust with anthropogenic contaminants spreads throughout the region and falls in the deposition areas affecting soil quality (Othman, Mat Jafri and San, 2010).
Recent studies have shown that in urban locations, transport is not only the source of gas emission but also the main source of trace elements input to the soil through “the exhaust of diesel and petrol, corrosion of metallic parts, engine wear, tire and brake pad wear and road surface degradation by vehicular movement” (Gupta, 2020). Some of these trace elements, such as cadmium, chromium, lead and nickel, deposit on the soil surface. These trace elements accumulate within the environment, which can affect humans and livestock health over time.
Dust blown from the soil surface can also carry trace elements. As it travels, the contaminants in the particulate matter can be enriched with emission from industrial and transport, and can cause additional health problems in urban areas. Severe trace element pollution was observed in dust collected from street pavements in Abadan, Iran (Islamic Republic of) in areas with dense vehicle traffic (Halil, Ghanavati and Nazarpour, 2019). Analysis showed that 97 percent of the samples had Nemerow Integrated Pollution Index values greater than 3 (Halil, Ghanavati and Nazarpour, 2019). This is a high level of pollution even for densely populated areas with heavy traffic.
Monitoring indoor house dust and outdoor street dust for cadmium, chromium, lead, nickel and zinc was carried out at 76 sites in Bahrain. Lead was predominant among the trace elements in areas with heavy traffic. Trace elements were double the average background levels in less dense traffic areas, with overall mean concentrations of indoor dust of 517, 202, 1.9, 11, and 10 mg/kg for lead, zinc, cadmium, chromium, and nickel respectively, compared with mean street dust values of 742, 67, 1.5, 9.6, and 12 mg/kg (Madany, Salim Akhter and Al Jowder, 1994). Automobile exhausts and wind-blown contaminated dust were the main sources of lead and nickel in both the house and street dust. Madany and co-workers (1994) indicated that the higher concentration of cadmium, chromium and zinc in the indoor samples was associated with galvanized metals, car tyres, cosmetic products, batteries and chrome plating. This indoor dust may be a significant source of human exposure to trace elements, especially for children, and may put food safety at risk.
An assessment of particulate matter size composition in the United Arab Emirates showed that the coarse fraction with diameters less than 10 µm (PM10) is associated with natural sources such as dust storms, crustal matter, and sea salts. The dominant elements are silicon, calcium, aluminium, magnesium, chlorine, potassium, iron and titanium with traces of chromium, manganese, nickel, vanadium, copper, zinc and strontium (Hamdan, Alawadhi and Jisrawi, 2015). The fine and ultrafine fraction (PM2.5) contains compounds that were created by the reactions of natural coarse contaminants with anthropogenic emissions such as sulphur dioxide (S02) and nitrogen oxides (NOx), during their transport in the atmosphere. (sulphur, chlorine, potassium, calcium and aluminium, silicon and smaller amounts of iron and zinc with a trace of vanadium). The assessment of the composition of particulate matter at two sites in the northern and south eastern parts of Urmia Lake, Iran (Islamic Republic of), from January to September 2013, showed a tenfold difference in concentrations between the two sites for lead, vanadium, nickel, arsenic, lanthanum and barium. This indicated enrichment by contaminants of anthropogenic origin, such as incineration of fossil fuels and biofuels (Gholampour et al., 2017). While concentrations of lead, arsenic and cadmium in suspended particles and PM10 were within the permissible levels, nickel exceeded European Union standards, which indicates it might cause environmental damage. In addition to the direct risk to human health through inhalation of the contaminated PM, it also poses an indirect risk by depositing on the surface of the soil and plant cover and thus entering the food chain.
Another environmental survey assessed the pollution and ecological risk from dust in main streets of Eastern and Southern Tehran, Iran (Islamic Republic of) (Saeedi, Li and Salmanzadeh, 2012). Fifty samples of street dust were analysed for trace elements (copper, chromium, lead, cadmium, nickel, zinc, iron) and polycyclic aromatic hydrocarbons (PAHs). The correlation, cluster and principal component analyses indicate that manganese and lithium were likely to originate from geogenic sources, while anthropogenic sources would account for the PAHs and copper, chromium, lead, nickel, zinc, and iron contaminants. The levels of contamination presented high ecological risk.
Air pollution caused by the Gulf War in early 1991 has also been investigated (El-Shobokshy and Al-Saedi, 1993). The disturbance of the desert land surface by the large number of tanks and other vehicles contributed to the intensity of dust storms in Saudi Arabia. Immediately after the war, the concentration of very fine dust particles (<15 μm) increased by 50 percent in comparison to the pre-war period. In addition, oil fires and military operations in Kuwait caused a significant increase of PM10 in the Saudi Arabia during the post-war period. It resulted in non-accidental mortality, estimated at 1 225 deaths, with an average exposure-response relative risk factor of 3.1 percent for every 50 µg cm3 increase in PM concentration (White et al., 2008). The long-term effect of continued accumulation of contaminated dust in agricultural soils needs to be monitored and evaluated.
Schoolchildren in urban, suburban and residential areas in Jeddah, Saudi Arabia, were checked for toxicological risks derived from particulates migrating inside classrooms (Alghamdi et al., 2019). Analysis of particulates identified the presence of the following trace elements (from highest concentration to lowest): cadmium, lead, zinc, arsenic, copper, nickel, manganese, chromium, cobalt, vanadium and iron. The concentrations of cadmium and lead indicated moderate to high levels of pollution, while those of arsenic and zinc were indicative of moderate levels of pollution. The risks were higher in urban schools and lower in residential schools, while the main routes of exposure were ingestion, dermal contact and, to a lesser extent, inhalation. Using different enrichment and hazard indicators, the authors concluded that cancer risks, due to exposure to trace elements in urban and suburban schools in Jeddah, exceeded the acceptable range as defined in national legislation.
A study in Algeria indicated that the transport sector, open burning of municipal wastes and heavy industries cause the emission of particles that pollute the surrounding air and are deposited on arable lands (UNEP, 2015). Within 1 km of the “Oued Smar” landfill, the concentration of dust concentration in the air exceeds 780 mg/m3, which is 78 times higher than the national permissible level. Qatar, Saudi Arabia and Egypt occupy the top three places in the world in the WHO classification of the annual average amount of PM2.5 in the air. These countries frequently exceed 100 µm/m3 due to development, the oil industry and desert dust particles. In addition, a “black cloud’’ over Cairo has been reported due to agricultural fires (WHO, 2017). According to this study, two cities in Iran (Islamic Republic of) (Zabol and Boushehr), three cities in Saudi Arabia (Riadh, Aljubail and Dammam) and two cities in Bahrain (Ma’ameer and Hamad Town) were ranked among the 20 cities most affected in the world by air contamination from petrochemical industries, vehicles and dust storms.
The trace element composition of dust deposition on tree-leaves can be used as a cost-effective bio-indicator to assess the impact of pollution caused by atmospheric dust deposition on arable lands. This deposition affects the quality of drained rainwater, which ends up in rivers and can flood agricultural land. A study in Isfahan, Iran (Islamic Republic of), showed that this technique was feasible for the assessment of ecological risks from the atmospheric deposition of dust contaminated with copper, iron, manganese, nickel, and zinc. The technique was not effective for assessing such risks associated with lead (Norouzi et al., 2015).
Radioactive fallout from past nuclear tests and accidents could be a concern for public health and the environment in the region. This can be exacerbated by its transport by dust storms. In Egypt, the concentration of rare earth elements, found together with radioactive thorium, varies between 1 µg/g and 60 µg/g and has been linked to long-range dust deposition (Shaltout et al., 2013).
The intensification of agriculture has long been a priority to address the food security of a growing global population. Despite the availability of more sustainable practices, such as conservation agriculture, agroecological, integrated pest management, and organic production, much agricultural production still relies on disruption of the soil and the intensive application of pesticides and fertilizers. Fertilizers and pesticides are applied seasonally to agricultural soils, which may cause a harmful accumulation of contaminants. This is exacerbated by the use of hazardous, inappropriate and illegal pesticides. Several studies in the region have reported soil and groundwater pollution by pesticides and nitrates due to excessive use of agrochemicals (Darwish et al., 2011a; Ghanem, 2005). Contaminants may also accumulate in the soil through the application of manure and biosolids as fertilizer, and through irrigation with wastewater. These materials can contain trace elements and other contaminants.
Agriculture is the main user of pesticide in the NENA region, with a total annual quantity exceeding 49 000 tonnes (FAOSTAT, 2019b). The region is subdivided into four groups according to pesticide use and agricultural area. Large pesticide users comprise Morocco, Egypt, Algeria, Saudi Arabia and Iran (Islamic Republic of), with annual consumption between 4 480 and 13 700 tonnes. However, in terms of pesticide use per area of cultivated land, this classification changes from a lowest application for Iran (Islamic Republic of) (0.27 kg/ha) and highest application for Egypt (2.15 g/kg). The second group comprises Sudan, Jordan, Lebanon, Syrian Arab Republic, Palestine and Tunisia with annual consumption between 1 000 and 2 500 tonnes. These countries apply pesticides as low as 0.2 kg/ha for Syrian Arab Republic and as high as 7 kg/ha and 9 kg/ha for Lebanon and Palestine respectively. The third group comprises Libya, Oman, Iraq and Yemen, whose annual consumption varies between 100 and 600 tonnes with the lowest application dose (<0.2 kg/ha) for Iraq, Sudan and Yemen and 3.44 kg/ha for Oman. Qatar, Kuwait, Mauritania and Bahrain consume the least pesticides per year, with annual consumption less than 100 tonnes. These countries apply <0.1 kg/ha in Mauritania and 2.0 kg/ha in Kuwait and Bahrain against 4 kg/ha in Qatar. While pesticide consumption in Algeria and Saudi Arabia increased steadily between 2000 and 2014, in the late 2010s it decreased in Egypt, Iran (Islamic Republic of), Morocco, Libya and Yemen. The promotion of more sustainable agricultural practices seems to be behind the decline in the first three countries, but the decrease in Libya, Mauritania and Yemen may be linked to destabilizing armed conflicts. In the region, there is also a risk of spraying locust on agricultural and desert lands in addition to the smuggling of illegal pesticides along unmonitored borders with the consequent risk of uncontrolled use. Similar risks imply the need for public health and disease vector control in the region.
In Palestine, the deterioration of soil and groundwater quality of the Gaza Strip (Figure 4) was attributed to: saline water intrusion; inappropriate solid waste disposal; the overuse of fertilizers, pesticides and soil amendments; and irrigation with low-quality wastewater (Alfarra and Hamada, 2019). An estimated 97 percent of irrigated land in the Gaza Strip is treated with pesticides, with a total quantity of pesticides almost equal to that of the West Bank, despite the massive difference in agricultural area. This is due to the excess application of pesticides of 7.7 L/ha in Gaza Strip against 1.8 L/ha in West Bank (Al-Sa‵ed, Ramlawi and Salah, 2011). The Palestinian agricultural sector in both the West Bank and the Gaza Strip, used methyl bromide as a soil disinfecting gas in greenhouses in 2005 at an annual rate of 372 tonnes per year, which was decreased to 111 tonnes in 2006 (Al-Sa‵ed, Ramlawi and Salah, 2011). This practice probably had an adverse impact on soil biodiversity and soil quality. Public health and ecosystems in Palestine were both affected by the deterioration soil and water quality due to the use of pesticides and herbicides in agriculture (Ghanem et al., 2011). An annual pesticide application of approximately 730 tonnes in the West Bank was reported by the Applied Research Institute in Jerusalem (Ghanem, 2005). Palestinian soils are also over-fertilized leading to nitrate contamination of the soil and the food chain. A statistical study carried out in both the West Bank and Gaza Strip showed that 217 pesticide products and 13 soil fertilizers were used. These included 134 different active ingredients applied in 62 insecticides, 45 fungicides and 20 herbicides (Al-Sa‵ed, Ramlawi and Salah, 2011). With actual applied pesticides rates of 7.7 L/ha and 1.8 L/ha in the Gaza Strip and the West Bank, the authors conclude that between 1996 and 2007, the use of insecticides was reduced by 30 percent, fungicides by 53 percent and herbicides by 64 percent (Al-Sa‵ed, Ramlawi and Salah, 2011). This outcome indicates improvements in pest management decision-making, and increased user and public awareness. The shallow aquifer of the West Bank is significantly affected by agricultural activities with groundwater concentrations of nitrates and sulphates exceeding WHO standards (Ghanem, 2005). A similar situation has been described in the Bekaa Plain, Lebanon (Darwish et al., 2011a).
Recent reports from Tunisia indicate that intensive use of pesticides and agrochemicals and the non-compliance with retention time between application and harvest as major threats to the environment and human health (Jeder et al., 2018).
Studies from Iran (Islamic Republic of) showed that high concentrations of trace elements in cultivated soils were due to over-fertilization and excessive application of pesticides to repel and kill plant pests, weeds and rodents (Atafar et al., 2010).
Phosphorus based fertilizers may contain trace elements as impurities, mainly cadmium, zinc, lead, copper, antimony, silver, lead, niobium and molybdenum (Azzi et al., 2017). Based on agricultural practices and the excessive application of fertilizers prevailing in the Eastern Mediterranean countries, the estimated average annual load of contaminants is: zinc (922 g/ha), copper (124 g/ha), lead (26 g/ha) and cadmium (6 g/ha). This burden may be tolerable in the short-term, but in the long-term, it might lead to accumulation of trace elements in the soil. The average trace element content (lead, cadmium, nickel, cobalt and chromium) of the fertilizers marketed in the Saudi Arabia (El-Taher and Althoyaib, 2012) and Lebanon (Bashour et al., 2004) were within the thresholds reported worldwide. However, in Lebanon, the granular phosphate fertilizers were highly enriched with trace elements, followed by the liquid fertilizer forms, with the lowest concentrations of trace elements detected in soluble crystalline fertilizers. Excess application of fertilizers can trigger additional input of trace elements beyond the recommended application and load (Darwish et al., 2011a).
Analysis of agricultural soils in seven regions of the northern Jordan valley revealed high concentration of lead (50 - 150 mg/kg), zinc (100 -300 mg/kg) and cadmium (4 - 7 mg/kg). These contaminant levels resulted from the use of poor quality irrigation water, and the application of fertilizers and pesticides (Abu-Rukah and Samawi, 2000).
The use of antimicrobials in livestock production for growth promotion, disease prevention and control can lead to the transference of unused antimicrobials and resistant microbes to faecal matter. The application of uncomposted manure and slurry as fertilizers are also quite frequent practices in the region. Both practices deserve particular attention as a potential source for pollution by unused antimicrobials and resistant microbes. In addition, pathogens, pharmaceuticals and personal care products in wastewater and sludge can pose a problem for soil and food quality if used. These sources should be considered as a potentially damaging effect on the soil ecosystem, as they can transfer into the food chain with consequences for human health.
Several studies from the region mentioned that industrial activity was one of the main sources of soil pollution. The principal industries in the region are: manufacture of paper, plastic and pipes; cement industry; food processing; construction; oil extraction, transportation and refining; and energy production. Industry, with its concentrated plants, is cited as one of the main sources of emissions leading to soil pollution by trace elements (arsenic, barium, cobalt, chromium, nickel, and zinc) in the NENA region.
Studies often report pollution of irrigation canals and agricultural soils adjacent to industrial areas. An ecological risk assessment of trace elements, carried out in El Sadat City, Egypt, showed an enrichment factor ranging from moderate (5) to high (10), especially for arsenic, compared to the average values found in the soils of the Nile Delta (Badawy et al., 2016). In Iran (Islamic Republic of), the industrial activities around the Hara Biosphere Reserve, on the Straits of Hormuz include the Queshm lead and zinc smelter, the AlMahdi aluminium company and the Hormozgan cement factory. There is also oil transport, commercial ships, and recreational boat traffic. These were identified as the most important sources of trace elements (lead, cadmium, nickel and iron). Cadmium had the highest enrichment factor, ranging from uncontaminated to strongly polluted sites (Nowrouzi and Pourkhabbaz, 2014). Trace elements associated with blown soil particles in Shiraz, Iran (Islamic Republic of), were found to have geogenic and anthropic origins. The main anthropogenic sources were traffic and industrial activities, with a high hazard index and mobility factor, characterized by the risk of transfer and uptake by edible plants. The mobility factor varies between 79.2 percent for lead, 74.6 percent for mercury, 64.1 percent for zinc and 56.4 percent for manganese. These contaminants require special attention due to the environmental and health impact (Keshavarzi et al., 2015).
The assessment of trace element pollution from industrial sources revealed that the topsoil (0-10 cm) from all surveyed sites in the Omdurman industrial area, in the Sudan, contained cadmium (1 mg/kg), chromium (30 mg/kg) and copper (20 mg/kg), all of which exceed normal values according to WHO. Conversely, most concentrations of nickel, zinc, cobalt, and lead were below normal values (Ali and Ateeg, 2015).
Another example of soil pollution from industrial activities in the region was reported in Algeria, where the analysis of agricultural soils near a cement factory revealed concentrations of PAHs of 2 103 ng/kg which exceeds the threshold values of the Hazardous Substances Data Bank (National Library of Medicine, 2020) and so represents a potential toxicological risk due to their carcinogenic and mutagenic properties (Mebarka et al., 2012).
In the NENA region, solid waste management (SWM) mainly consists of collecting and transporting solid wastes, and depositing them in landfills or uncontrolled open dumps. The landfills and dumps often receive domestic, hospital and industrial wastes, which become mixed in the landfill and are often burned. More than 81 million tonnes of municipal solid waste (MSW) are generated each year in Egypt, of which less than 20 percent is adequately treated and less than 5 percent is recycled (Mostafa, 2020). Where hospitals lack medical waste incinerators, hazardous medical waste can be disposed in an uncontrolled manner. For instance, in Iran (Islamic Republic of), more than 2 000 tonnes of hazardous medical wastes including infectious, toxic, spontaneously combustible materials, and potentially carcinogenic, corrosive and reactive substances was disposed in the same landfill as domestic wastes without any control (Hassanvand et al., 2011).
Lebanon has a network of central and large dumping sites in addition to 941 small landfills spread throughout the country. Many are operated inappropriately, including by open burning, which pollutes the air with PM, threatening public health and the soil-groundwater system (HRW, 2019). At some of these sites the fires are continuous and self-sustaining. Chronic respiratory diseases from areas surrounding these sites are frequently reported while solid waste management is practised without an integrated strategic vision and sustainable approach (Halwani et al., 2020). In the absence of more sustainable SWM capacity, uncontrolled dumping on hillsides and seashores is the most common method of solid waste disposal as shown in Figure 5. Dumping sites in mountainous karstic areas can pollute soil and groundwater through leachate seepage.
The leachate from solid waste within the landfill of Ain-El-Hammam municipality, Algeria, affected soil quality by increasing the organic matter by up to 4.5 percent. It also resulted in the accumulation of copper, zinc, cadmium, nickel and chromium in the soil (Mouhoun-Chouaki et al., 2019).
The law on solid waste adopted in Morocco in 2006 represents a strategic legal, institutional and financial framework. Of the 6.8 million metric tonnes of domestic waste and 1.6 million metric tonnes of industrial waste generated annually in Morocco, 85 percent is collected, mainly in urban areas. However, less than 40 percent is disposed in controlled landfills (Dahchour and Hajjaji, 2020a).
In Tunisia, all solid waste and 98 percent of liquid waste used to be collected, appropriately disposed, treated or recycled (Mahjoub, Jemai and Haddaoui, 2020). However, secondary treated wastewater is frequently released into open water bodies (Mahjoub, Jemai and Haddaoui, 2020). Since 2011, with the decentralization of governmental control, NGOs and municipalities have increasingly reported finding pharmaceutical and industrial micro-contaminants in water and soils surrounding landfills.
In Palestine there is insufficient capacity to collect and transport the 2 353 tonnes of domestic waste that arises daily due to the lack of waste collection vehicles (Yaqob, 2020).
In Egypt, Elbasiouny et al. (2020) suggested alternative waste management methods to the prevailing open burning and other unsafe disposal practices. Their proposed methods aimed to mitigate greenhouse gas emissions and climate change, and included: the management of agricultural waste to produce animal feed, composting, bioenergy generation, and manufacture of bioplastic and building materials. Anaerobic digestion and pyrolysis have been suggested as alternative management practices at the waste dumping site at Makkah, Saudi Arabia, (Anjum et al., 2016). Treatment of the organic fraction of municipal solid waste by anaerobic digestion can produce methane as biofuel. Pyrolysis of non-biodegradable plastics can produce a variety of value-added products such as char, and liquid and gaseous fuels. Segregation of municipal solid waste into fractions for processing separately can form part of a sustainable waste management strategy. In the Khenifra region of Morocco, biodegradable organic matter was separated and composted, while glass, paper, and plastics were recycled (Elhamdouni et al., 2019). The possibility of converting biomass, consisting of agricultural residues and animal wastes, into biofuels has been explored to treat the increasing quantities of solid waste in Yemen (Zabara and Ahmad, 2020).
In 2016, Tunisia generated 250 000 tonnes of plastic waste, 20 percent of which remained uncollected. Sixty percent of the collected waste was sent to landfills, 16 percent was openly dumped in the countryside, and only 4 percent was recycled (WWF, 2019). Approximately 8 500 tonnes of its plastic waste end up in the Mediterranean Sea each year, breaking down into microplastics, which are increasingly recognized as an important pollutant and a transport mechanism for other contaminants. Tunisia’s economy loses an estimated USD 20 million annually due to the adverse impacts of plastic pollution on tourism, shipping and fishing.
The exploitation of mineral resources from quarries and mines can be a source of contamination that can affect the quality of agricultural soils. In an agricultural area adjacent to a mineral mine in Old Jebel Ressas, Tunisia, high concentrations of lead, cadmium and zinc were found in arable lands, with decreasing concentration along downstream due to the dilution effect (Attia et al., 2018a). An analysis of the effect of mine tailings around agricultural soils showed that the concentration of the trace elements in the tailings exceeded by 30-100 times the content for safe soil, for zinc (202 mg/kg), lead (125 mg/kg) and cadmium (0.4 mg/kg) (Attia et al., 2018b). These contaminants are spread on agricultural soils by wind and water erosion. In Lebanon, elevated concentrations of trace elements persisted in soils and water bodies below a quarry until the closure of the mining site (Korfali and Davies, 2005). The ecological risk that emerged from mining activities in the Lebanese mountains was analysed by Darwish et al. (2011b) and showed the adverse impact of unsustainable mining practices on soil quality, biodiversity and ecosystem services (Khater and Martin, 2007).
An assessment of land and soil pollution in the surroundings of a phosphate mine and fertilizer manufacturing area in northern Lebanon showed an exogenous accumulation of lead radionuclides on the soil surface. This was due to the alkaline pH of the soil and its high organic matter content, with decreasing values at lower soil horizons (Saba et al., 2019). Air emissions, the discharge of liquid effluents and large volumes of solid waste from phosphate and potash mining in Jordan (Figure 6), are also causing negative environmental impacts. The processing of phosphate ores generates a concentrate of phosphatic minerals and an enormous volume of undesirable fine-grained rock and minerals particles called phosphogypsum, which contains radioactive uranium and radium (Alrawashdeh and Thyabat, 2012). The disposal of saline by-products from potassium mining from the highly salty Dead Sea might result in induced salinity of surrounding arable lands. Alrawashdeh and Thyabat (2012) concluded that there was a lack of an effective monitoring programme and poor of enforcement mining regulations. There was also a lack of advice on the restoration policy and methods to reduce the visual impact of mining waste.
Severe environmental damage from gold mining, such as dust and gas emission, deforestation, mercury pollution and the deterioration of landscape, have been observed in the Republic of the Sudan (Ibrahim, 2015). Cultivated soils in the vicinity of the Zaida mine (Hight Moulouya, Morocco) showed elevated concentrations of cadmium (33 mg/kg), copper (77 mg/kg), zinc (206 mg/kg), and lead (831 mg/kg) (Laghlimi et al., 2018). The trace element content in agricultural soils is negatively correlated with the distance of the mining tailings and positively correlated with the direction of prevailing winds.